1. Field of the Invention
This invention relates to a high frequency scalpel system, and more particularly to a high frequency scalpel system including an electrode functioning as a scalpel proper and a high frequency oscillator circuit adapted for supplying high frequency current to the electrode, and also to an endoscope making use of such a high frequency scalpel system.
2. Description of the Prior Art
A high frequency scalpel may be used in a known manner for cutting an affected portion of a living body, or stopping bleeding thereat, by means of a Joule's heat generated at a portion thereof by supplying a high frequency current of a frequency ranging approximately from 300 kHz to 1 MHz between a scalpel or therapuetic electrode and a planar electrode contacted with the affected portion.
In general, a scalpel may work in three operating modes: cutting, coagulation and blend modes. In a cutting mode, an affected portion is cut out or incised under continuous application of high frequency current. In a coagulation mode, hemostasis is effected by protein coagulation of the affected portion resulting from intermittent application of high frequency current. A blend mode is a mixed mode of the cutting and coagulation modes. In any of these modes of the high frequency scalpel, a high frequency current with a maximum power output of several hundreds of watts and a peak voltage of approximately three thousand volts, by way of an example, is supplied to the electrodes. Hence, when a high frequency scalpel is used in conjunction with a medical TV system or an endoscope employing a solid state imager, a high frequency noises resulting from the operating current for the scalpel may be mixed into a video signal for the endoscope or TV system. This may cause flickers, smears or stripes in a picture displayed on a screen so as to make it difficult to view the picture on the screen.
For instance, in an endoscope employing a solid state imaging device such as a charge coupled device (CCD) or bucket brigade device (BBD), referred to as a charge transfer device (CTD), where a video signal line, adapted for transmitting a video signal from a solid state imaging device mounted in a viewing head of the endoscope is installed within an endoscope sheath in a side by side relationship with a high frequency power source line adapted for supplying a high frequency drive signal to the scalpel electrode mounted in the viewing head, electromagnetic coupling may be caused between the video signal line and the high frequency source line. In such a case, it may be difficult for an operator to view an endoscope image, that is, a picture, indicative of the inside of a cavity into which a viewing head of the endoscope is inserted, and displayed on a video display device such as cathode ray tube (CRT) provided in an operating unit of the endoscope.